# Homework Help: Voltage Drops - Really Struggling!

1. Apr 1, 2016

### scarecrow75

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Hi all

Wondering if anyone can help. Really dont know where to start

I know Zs = Ze + Z1 + Z2

and Z1 = PCR 8.9 milli-ohms/meter
and Z2 = CPC 14.5 milli-ohms/meter
which equates to 0.0234X milli-ohms/meter over X meters

but where does my volt drop come in if I dont know my current?

Regards

2. Apr 1, 2016

### CWatters

If the fuse is 32A the current could be any value <32A ??

3. Apr 1, 2016

### scarecrow75

1. The problem statement, all variables and given/known data
230 V, 50 Hz supply (TN)
Ze = 0.8 ohms
Z1 = 8.9 milli-ohms/meter
Z2 = 14.5 milli-ohms/meter
Volt-drop/Amp/meter = 18 mV/A/m
2. Relevant equations
Zs = Ze + Z1 + Z2
V / Zs = I ??????

3. The attempt at a solution
Zs = Ze + Z1 + Z2
Zs = 0.8 + (0.0089 + 0.0145)X..........................where X is the distance in meters
Zs = 0.8 + 0.0234X

Then
230V / (0.8 + 0.0234X) = I

Not sure if this is correct!
Also is this relevant:
TN system.... I know that for final circuits up to 32A disconnection time should not exceed 0.4secs
Voltage Drop, lighting circuits = 3%max and other circuits 5% max
if this is correct then 230V * 0.05 = 11.5V

Not sure if this is right approach

Any help?

Cheers

4. Apr 2, 2016

Anyone????

5. Apr 2, 2016